This invention relates generally to fuel oil, gas or waste oil-burning furnaces and relates, more particularly, to such furnaces of a forced-air type for heating air in climate control applications.
Forced-air furnaces employing oil or gas burners commonly include a ceramic combustion chamber within which combustion of the fuel takes place and a heat exchanger positioned about the combustion chamber for receiving heat generated within the chamber. The combustion chamber typically operates at high temperatures and for some furnaces is a frequent failure point. Combustion chambers are usually constructed of heavy materials so they are designed to a minimum size to hold down cost and weight, but operating temperatures are usually inversely proportional to chamber size. As the chamber becomes smaller, operating temperatures usually become greater. The combustion chamber is also exposed to the products of combustion which may include contaminants that will cause chamber failure. Thus, combustion chamber design is one of the more difficult design challenges in manufacturing a furnace.